#include <stdio.h>
#include <stdlib.h>
#include <string.h>


#include <unistd.h>
#include <pthread.h>
#include <sys/socket.h>
#include <arpa/inet.h>


#define BUF_SIZE 100
#define MAX_CLNT 256

void * handle_clnt( void * arg );
void send_msg( char * msg, int len );
void error_handling( char * msg );


int  clnt_cnt = 0;
int clnt_socks[ MAX_CLNT ];
pthread_mutex_t mutex;

int main( int argc, char *argv[])
{
    int serv_sock;
    int clnt_sock;

    struct sockaddr_in serv_adr;
    struct sockaddr_in clnt_adr;

    int clnt_adr_sz;
    pthread_t t_id;
    if ( 2 != argc ) {
        printf("Usage : %s <port>\n", argv[0]);
        exit( 1 );
    }

    pthread_mutex_init( &mutex, NULL );
    serv_sock = socket( PF_INET, SOCK_STREAM, 0 );

    memset( &serv_adr, 0, sizeof(serv_adr));
    serv_adr.sin_family = AF_INET;
    serv_adr.sin_addr.s_addr = htonl( INADDR_ANY );
    serv_adr.sin_port = htons( atoi( argv[1]));

    if ( -1 == bind( serv_sock, 
            (struct sockaddr*) &serv_adr, sizeof(serv_adr))) {
        error_handling(" bind error");
    }

    if ( -1 == listen( serv_sock, 5)) {
        error_handling("listen() error");
    }

    while (1)
    {
        clnt_adr_sz = sizeof( clnt_adr );
        clnt_sock = accept( serv_sock, 
            (struct sockaddr *) &clnt_adr, &clnt_adr_sz);

        pthread_mutex_lock( &mutex );
        clnt_socks[clnt_cnt++] = clnt_sock;
        pthread_mutex_unlock( &mutex );

        pthread_create( &t_id, NULL, handle_clnt, 
            (void *) &clnt_sock);
        pthread_detach( t_id );
        printf("Connected client IP: %s \n", inet_ntoa(clnt_adr.sin_addr));

    }
    close( serv_sock );


    return 0;
}


void * handle_clnt( void * arg)
{
    int clnt_sock = *((int *) arg);
    int str_len = 0;
    int i;
    char msg[BUF_SIZE];

    while (0 != (str_len = read(clnt_sock, msg, sizeof(msg))))
        send_msg( msg, str_len );
    pthread_mutex_lock( &mutex );
    for (i = 0; i < clnt_cnt; i++)
    {
        if ( clnt_sock == clnt_socks[i]) {
            while ( i++ < clnt_cnt -1)
                clnt_socks[i] = clnt_socks[i + 1];
            break;
        }
    }
    clnt_cnt--;
    pthread_mutex_unlock( &mutex );
    close( clnt_sock );
    return  NULL;

}

void send_msg( char *msg, int len)
{
    int i;
    pthread_mutex_lock( &mutex );
    for ( i = 0;i < clnt_cnt; i++)
        write( clnt_socks[i], msg, len);

    pthread_mutex_unlock( &mutex );
}
void error_handling( char *msg )
{
    fputs(msg, stderr);
    fputc('\n', stderr);
    exit(1);
}